100 CALIFORNIA ACADEMY OF SCIENCES. 



PLATE XXXIV. 



PONTODRILUS MICHAELSENI. 



'JU. A somewhat dingrniumntiv view of tlip anterior somites Heeii in loii^-itiKliiml section. I>r. brain, mo. month. 

 /i/i.r. jiharynycal cavity. ;</i2'. pharynx, m. nniKCiilur strand connectin).; |iharynx with the lioily-wall. nl.ijl. khI- 

 ivary or [iliaryngenl (,'hiu(ls opening by ducts in the pharynx, the ducts being snpported by njnscnlar strands 

 (stained yellow), gn. ijl. smaller gland; connected with blood vessel. ;//. glands connected with the lateral vessels. 

 le. cesophagMS. iZ. ii. dorsal blood vessel. «. septa. «/<<A. spermatheca, and their diverticula. The lower end 

 of the spermatheca is greatly enlarged, forming propiilsory bursa. KjHh. p. spermathecal pore. I. testes. 

 01). ovaries, ovd. oviduct, c r. ciliated rosettes. A. hearts, sp. s. sperm-sacs. These sacs are principally 

 ventral to the oesophagus. Hc/<Ar. nephridia, the most anterioroue is found in somite xiii. r/. clitellnm. yl.er. 

 glandular crop in shape resembling a gizzard, s.i. sacculated iutestine. //r. prostate. ^ the muscular duct 

 of the prostate cut through, c. c. copulatory cushion. The dotted line indicates the outlines of the duct as 

 they ajipcar in other sections. 



.'to. Section through the posterior part of the pharyngeal glands, showing the arrangement of the glands, dncts, 



muscles and blood vessels, all in vertical section, /p. cesophagus. (/). inner epithelial lining, m. <r. circular 



lesophageal muscles, m. muscular strands, phx. gl. pharyngeal gland. //. r. dorsal vessel. 



In this figure the glands are stained violet, the muscles appear as yellow and the ducts are dark violet. The 



blood vessels are black (Corosive sublimate, abs. alcohol, orange G. amm. hiematoxylon. Thus in xylol. 



This and the following five figures are all drawn from sections treated in the same way.) 



.'tl. .\ longitudinal section of a lobe, showing the general arrangement of the glands and ducts, due. ducts from 

 the gland, leading anteriorly to the pharynx. ;//. c. glandular cells. hi. <jL blood glands. m. supporting 

 muscular strands, hi. r. blood vessels. 



.'t'2. .\ small glandular lobe more highly magnified. The letters indicate the same as in the preceding figure. The 

 nuclei are stained yellowish with orange G. The secretion of the cells is preciiiitated ? and stained dark violet 

 with amm. h.'ematoxylou. 



.S.S. A part of a glaud, with supporting muscles. 



.'M. Two sections of muscular strands, showing the connection with the ducts in which the secretion has been 

 stained deep blue. 



3"). One of the glandular cells with nucleus stained yellow. The vacuoles (im.) are white, the protoplasm grayish, 

 while the secretions are stained dee]) bluish-violet. 



.'IGA. The proximal end of two glandular ducts where they penetrate the epithelial lining of the pharynx, near its 

 dorsal side, showing theductules or eud dncts leading between theepithelial cells, hi. blood vessels, m. ;<A. 

 supporting muscles for the ducts connecting with pharynx. I. m. transversal muscles cut ocross. ijl. d. 

 glandular ducts leading from the gland at the distal eud beyond the pharynx. These ducts are the largest 

 and collective ones, having received the secretion from many smaller ducts. </>. epithelial cells lining the 

 pharyngeal cavity, ijl. dt. glandular ductules passing between the former into the pharyngeal cavity, n.gl. 

 two of the smallest of the salivary glands, a few of which are found at the periphery of the pharynx. 



.'KiH. A longituilinal section of one of the small septal glands, one pair of which is found in v, vi, vii, viii, ix. 

 '■. /./. V. connecting blood vessel between the ventral vessel c. hi. vi and the dorsal vessel. This vessel is 

 cut in two places, the one marked <■. hi. vii being nearest to and just below the (esophagus {le. v.) the ventral 

 outline of which only is figured diagrammatically. n. septum, outline of, between vi. vii. ;//. small glands, a 

 few of which surround the somewhat larger septal gland. «. ijl. the largest septal gland, ip. r. wandering or 

 perigastric corpuscles, il. I. discharge ducts from glands, probably connecting with the pharynx. 



.'17. Cross-section of an immature specimen, through the inters<'gmeiital groove between somites xvii /xviii, just 

 anterior to the copulatory cushions. In this section no clitellar cells have yet developed on the ventral side 

 of the l>ody. hy. hypodcrniis. t. m. transverse muscular layer. /. m. limgitudinal niuscular layer, inph. 

 iiepliiUliuni. .v. «. septum between xvii/xviii. »h. muscles connecting the glandular part of the sperma- 

 theca with the body-wall. <//. /•>■. glandular i)art of the prostate, .i/id. the sperm-duct just entering the 

 glandular prostate, tii, /ir. muscular part of the iirostate. c. nr. ventral nerve cord. .v. i. sacculated intes- 

 tine. 



.'tS. C'ross-section of the body of an immature specimen, through somite xviii, the section passing through the 

 copulatory cushions and through a part in which the clitellar colls on the ventral side of the body are already 

 developed, a. m. arciform muscles connecting the copulatory region with the dorsal part of the boily-wall. 

 rl. r. clitellar colls developed in this somite only on the ventral side, never extending to the dorsal side even 

 in fully mature s])eciniens. Other letters indicate the same as in the preceding figure. 



;(!). ('ross-seitioii tliidugh somite xiii close to the anterior septum. The clitellar cells are here fully developed. 

 ». .1. part of septum between xii/xiii. rl. r. clitellar cells, only ilcveloped dorsally. r. rl. ventral termini of 

 the clitellar cellH. i.e. ovaries, iipd. siieriinluct. I. i. tubular intestine, dv. dorsal vessel A. hearts. 



